The purposes of this proposal are: A) To study the effects of estrogens and progestins in uterine (endometrial) primary explants and characterized cell lines on: 1) DNA, RNA and protein synthesis. 2) Presence and hormonal regulation of described rabbit uterine secretory proteins by the cultured cells. 3) The "per cell" number of estradiol and/or progesterone receptors. B) To develop and assay for chemical carcinogenesis in uterine fresh explants and cell lines. C) To determine a possible link between the hormonal effects and "in vitro" carcinogenesis.